The present invention relates to a capsule-type device which is capable of generating power, for example, by receiving a time-varying magnetic field generated by an external power source. The present invention further relates to a controlling system for such a capsule-type device.
Electronic endoscope systems for examining an internal body of a patient have been widely used. In general, such an electronic endoscope system includes an electronic endoscope which is inserted into the internal body of the patient, and a processor to which the electronic endoscope is attached. The electronic endoscope has an imaging device such as a CCD (charge-coupled device) at its tip portion to convert an image formed thereon by an objective lens to an image signal. The image signal is transmitted from the electronic endoscope to the processor to process the image signal. The image of a part of the internal body of the patient is thus obtained.
When an endoscopic examination is conducted for examining a digestive tube of the patient, an insertion tube portion of the electronic endoscope has to be inserted into the digestion tube of the patient. That is, the patient needs to swallow the insertion tube of the electronic endoscope, which causes pain to the patient.
Recently, capsule-type endoscopes have been proposed. The use of the capsule-type endoscope relieves the patient of the pain caused when the patient swallows the insertion tube of the electronic endoscope. The capsule-type endoscope has a small size so that the patient can swallow it. Further, the capsule-type endoscope is configured to obtain an image of the internal body of the patient and to transmit the image as a radio signal.
Japanese Patent Provisional Publication No. 2001-224551 discloses such a capsule-type endoscope. FIG. 15 is a block diagram of a capsule-type endoscope 100 disclosed in the publication. The capsule-type endoscope 100 is used as a part of a capsule-type endoscope system. The capsule-type endoscope system includes a processor and an external power source (not shown in FIG. 15), which are located outside of the patient body.
The capsule-type endoscope 100 is capable of communicating with the processor by a radio signal. The processor is used to remotely control the capsule-type endoscope 100 and to process an image signal transmitted from the capsule-type endoscope 100. The external power source supplies the capsule-type endoscope 100 with power by generating a time-varying magnetic field.
As shown in FIG. 15, the capsule-type endoscope 100 includes an objective lens system 101, an image sensor 102, a signal processing circuit 103, a transmitter 104 and a coil 105, which are enclosed by a casing 107. The objective lens system 101 forms an image of an object on the image sensor 102. The image sensor 102 converts the image formed thereon to an electric signal. The electric signal generated by the image sensor 102 is processed by the signal processing circuit 103 to generate an image signal. Then, the image signal generated by the signal processing circuit 103 is transmitted through the transmitter 104 as the radio signal.
The coil 105 is located on a portion of an internal surface of the casing 107 (i.e., (on the inside bottom surface of the casing in FIG. 15)) so that the coil 105 generates power by intersecting with a magnetic flux generated by the external power source.
When the capsule-type endoscope 100 is swallowed by the patient, the coil 105 of the capsule-type endoscope 100 receives the time-varying magnetic flux generated by the external power source and then generates power. The power generated by the coil 105 is supplied to various circuits including the image sensor 102, the processing circuit 103 and the transmitter 104 in the capsule-type endoscope 100.
Other types of the capsule-type device, configured to generate power by receiving a time-varying magnetic field and used to observe the internal body of the patient, are also proposed.
One of problems of the conventional capsule-type devices described above is that there is a case where electromotive force is reduced depending on an angle formed between the coil 105 and the magnetic flux generated by the external power source because the coil 105 is formed only on the portion of the internal surface of the casing 107.
Another problem of the conventional capsule-type device is that the capsule-type device existing in the patient body easily changes its attitude (i.e., orientation), for example, by peristalsis of the digestion tube of the patient. Therefore, it is very difficult to detect the attitude of the capsule-type device.